Add Windows 7 console handle workaround (revert 48042aa)

src/syscall/exec_windows.go

@@ -317,6 +317,17 @@ func StartProcess(argv0 string, argv []string, attr *ProcAttr) (pid int, handle
 		}
 	}
 
+	var maj, min, build uint32
+	rtlGetNtVersionNumbers(&maj, &min, &build)
+	isWin7 := maj < 6 || (maj == 6 && min <= 1)
+	// NT kernel handles are divisible by 4, with the bottom 3 bits left as
+	// a tag. The fully set tag correlates with the types of handles we're
+	// concerned about here.  Except, the kernel will interpret some
+	// special handle values, like -1, -2, and so forth, so kernelbase.dll
+	// checks to see that those bottom three bits are checked, but that top
+	// bit is not checked.
+	isLegacyWin7ConsoleHandle := func(handle Handle) bool { return isWin7 && handle&0x10000003 == 3 }
+
 	p, _ := GetCurrentProcess()
 	parentProcess := p
 	if sys.ParentProcess != 0 {
@@ -325,7 +336,15 @@ func StartProcess(argv0 string, argv []string, attr *ProcAttr) (pid int, handle
 	fd := make([]Handle, len(attr.Files))
 	for i := range attr.Files {
 		if attr.Files[i] > 0 {
-			err := DuplicateHandle(p, Handle(attr.Files[i]), parentProcess, &fd[i], 0, true, DUPLICATE_SAME_ACCESS)
+			destinationProcessHandle := parentProcess
+
+			// On Windows 7, console handles aren't real handles, and can only be duplicated
+			// into the current process, not a parent one, which amounts to the same thing.
+			if parentProcess != p && isLegacyWin7ConsoleHandle(Handle(attr.Files[i])) {
+				destinationProcessHandle = p
+			}
+
+			err := DuplicateHandle(p, Handle(attr.Files[i]), destinationProcessHandle, &fd[i], 0, true, DUPLICATE_SAME_ACCESS)
 			if err != nil {
 				return 0, 0, err
 			}
@@ -356,6 +375,14 @@ func StartProcess(argv0 string, argv []string, attr *ProcAttr) (pid int, handle
 
 	fd = append(fd, sys.AdditionalInheritedHandles...)
 
+	// On Windows 7, console handles aren't real handles, so don't pass them
+	// through to PROC_THREAD_ATTRIBUTE_HANDLE_LIST.
+	for i := range fd {
+		if isLegacyWin7ConsoleHandle(fd[i]) {
+			fd[i] = 0
+		}
+	}
+
 	// The presence of a NULL handle in the list is enough to cause PROC_THREAD_ATTRIBUTE_HANDLE_LIST
 	// to treat the entire list as empty, so remove NULL handles.
 	j := 0